I am sort of in the same boat - not bricked but trying to work out how to get there from here...
I have a TL-WR902-AC V3 - latest tplink firmware. I want to put openwrt on it. Everything I see says to connect an ethernet cable from my tftp server to the WR902 - I would do that, except my server is a Macbook Pro, has a default tftp server, but no ethernet. As I understand it, the TFTP server needs to be at a specific IP address, as well (192.168.0.66, as I recall) I cant see anything that says that tftp works over wifi. So my thought on a work around was to use a spare raspberry Pi 4 that I have - set it up with both a wifi connection (192.168.0.50) so that I can connect from my mac (192.168.0.120) and an ethernet connection (192.168.0.60) that I hardwire to the WR902 with an ethernet cable. (My existing primary router is already at 192.168.0.1 (do I need to move that?) I can then ssh into the pi from the Mac to turn on the tftp etc, and watch progress etc..
Does that sound like the best approach?